A New Approach for Understanding Lead Transfer in Agricultural Soil

Abstract

Surface water is frequently contaminated by the trace metals, in particular lead and zinc, produced by mining activities. The infiltration of this water is likely to pollute surface soils and ground water. The study of the transfer of trace elements, especially lead, under real conditions is difficult to carry out due to the physicochemical and hydrodynamic complexity of real soil (preferential flows, conditions of unsaturation...), of the presence of colloids and of many candidate elements. The objective of the present study was to gain a better understanding of the parameters influencing the migration processes of trace elements in simplified systems; it was based on the study of Pb transfer in laboratory columns filled with soil. The results showed that retention of lead in soil is strongly dependent on feed flow rate, particulate bed tortuosity, bed height, water–soil surface contact and volume of water. Increase in bed height, water–soil surface contact and particulate bed tortuosity leads to higher contact time thus higher lead retention by soil, whereas increase in feed flow rate and volume of water leads to lower contact time thus lower lead retention by soil.